State of knowledge

August 2023

The use of a Microsoft SQL Server Express Edition as a database for the UCServer cannot be recommended without restrictions.
Deployment should only take place if the alternatives are not an option, the necessary knowledge and skills are available, and the limitations/problems play a minor role.

This article explains why Microsoft SQL Server Express is only conditionally suitable for use with ProCall Enterprise and cannot be recommended by estos as a database for use in productive environments. We have compiled our experiences and findings here and point out that SQL Server Express is also recommended by Microsoft for a clearly defined target group and for testing purposes, for example. 

Excerpt from Microsoft's explanation of SQL Server Express

Quote: "Express edition is the entry-level, free database and is ideal for learning and building desktop and small server data-driven applications. It is the best choice for independent software vendors, developers, and hobbyists building client applications [...]"

(Taken from https://docs.microsoft.com/en-us/sql/sql-server/editions-and-components-of-sql-server-version-15)

Limitations of Microsoft SQL Server Express

The following limitations to the individual SQL Server Express editions are known.
(Taken from https://blog.officemanager.de/2012/01/sql-server-express-limits/, Last change 09.04.2020)

Important limitations of the Express Version 2019

  • Only one processor is used, but up to 4 processor cores.
  • Maximum used memory per instance: approx. 2 GB
  • A database may have a maximum size of 10 GB.
  • The SQL Server Agent service is not included.
  • Full-text indexing and searching are only available in the "Express with Advanced Services" edition.

Important limitations of the 2017 Express version

  • Only one processor is used, but up to 4 processor cores.
  • Maximum used memory per instance: approx. 2 GB
  • A database may have a maximum size of 10 GB.
  • The SQL Server Agent service is not included.
  • Full-text indexing and searching is no longer included in the free edition.

Important limitations of the Express versions 2012, 2014 and 2016

  • Only one processor is used, but up to 4 processor cores.
  • Maximum used RAM per instance: approx. 2 GB
    1 GB in the 2012 and 2014 versions
    2 GB in 2016 version
  • A database may have a maximum size of 10 GB.
  • The "SQL Server Agent" service, which controls automatic data backup, for example, is not included.
  • Full-text indexing and searching is only available in the "Express with Advanced Services" edition.

Possible effects in ProCall Enterprise

Due to the above restrictions, the journal and chat in ProCall may be affected when using Microsoft SQL Server Express.

Alternative solution/approach

up to 250 users: SQLite

Switch to the integrated SQLite database in ProCall Enterprise

from 250 users: SQL Server Standard

Switch to SQL Server Standard

As an entry-level variant, Microsoft SQL Server 2019 Standard can be licensed e.g. for 2 CPU cores.

Further information on the procedure for changing databases

For the procedure of changing the database for ProCall Enterprise, we have compiled information on migrating the data Microsoft SQL Server → SQLite: 
Best Practice: Data migration of UCServer database SQLite <-> Microsoft SQL Server